Polypropylene has been used widely in a molding field because it is excellent in mechanical properties, chemical resistance, and so on and therefore it is very useful. Foam molded articles obtained by foam molding polypropylene have been used as cushioning materials in the automobile field, acoustic materials, draining materials for percolation, various types of fillers, and so on.
JP 10-87919 A discloses a polypropylene resin composition obtained by melt blending (A) 50 to 95 parts by weight of a polypropylene having a melt flow rate (ASTM D1238, 230° C., 2.16 kg load) of 10 to 100 g/10 min, (B) 3 to 45 parts by weight of a non-crystalline or low-crystalline α-olefin copolymer, (C) 2 to 45 parts by weight of an inorganic filler (the total amount of the components (A), (B), and (C) is 100 parts by weight), and (D) 0.005 to 0.2 parts by weight of an organic peroxide, wherein the polypropylene resin composition is characterized in that (i) the melt flow rate (ASTM D1238, 230° C., 2.16 kg load) is 50 to 150 g/10 min, (ii) the IZOD impact strength (with a notch; ASTM D 628) at 23° C. is 100 J/m or more, and (iii) the tensile elongation at break (ASTM D638) is 20% or more.
JP 11-279369 A discloses a polypropylene resin composition obtained by mixing (A) 50 to 100 parts by weight of a propylene-ethylene block copolymer having a melt flow rate of 0.1 to 80 g/10 min and an ethylene content of an amorphous portion thereof of 30% by weight or more, (B) 0 to 35 parts by weight, based on the component (A), of a rubbery polymer, (C) 0 to 35 parts by weight, based on the component (A), of an inorganic filler, and (D) 0.005 to 0.2 parts by weight, relative to 100 parts by weight in total of the components (A), (B), and (C), of an organic peroxide, and then subjecting them to melt-kneading treatment.